title: Chemical-clathrate hybrid hydrogen storage: storage in both guest and host.
abstract: Hydrogen storage from two independent sources of the same material represents a novel approach to the hydrogen storage problem, yielding storage capacities greater than either of the individual constituents. Here we report a novel hydrogen storage scheme in which recoverable hydrogen is stored molecularly within clathrate cavities as well as chemically in the clathrate host material. X-ray diffraction and Raman spectroscopic measurements confirm the formation of beta-hydroquinone (beta-HQ) clathrate with molecular hydrogen. Hydrogen within the beta-HQ clathrate vibrates at considerably lower frequency than hydrogen in the free gaseous phase and rotates nondegenerately with splitting comparable to the rotational constant. Compared with water-based clathrate hydrate phases, the beta-HQ+H2 clathrate shows remarkable stability over a range of p-T conditions. Subsequent to clathrate decomposition, the host HQ was used to directly power a PEM fuel cell. With one H2 molecule per cavity, 0.61 wt % hydrogen may be stored in the beta-HQ clathrate cavities. When this amount is combined with complete dehydrogenation of the host hydroxyl hydrogens, the maximum hydrogen storage capacity increases nearly 300% to 2.43 wt %.
authors.affiliation: Chemical Engineering Department, Colorado School of Mines, Golden, Colorado 80401, USA.
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Strobel
authors.forename: Yongkwan
authors.initials: Y
authors.lastname: Kim
authors.forename: Gary S
authors.initials: GS
authors.lastname: Andrews
authors.forename: Jack R
authors.initials: JR
authors.lastname: Ferrell
authors.forename: Carolyn A
authors.initials: CA
authors.lastname: Koh
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Herring
authors.forename: E Dendy
authors.initials: ED
authors.lastname: Sloan